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We present a robust tool to analyze nonclassical properties of multimode twin-beam states in the mesoscopic photon-number domain. The measurements are performed by direct detection. The analysis exploits three different non-classicality…

Numerous non-classicality criteria based on the probabilities of experimental photocount or theoretical photon-number distributions are derived using several approaches. Relations among the derived criteria are revealed and the fundamental…

Quantum Physics · Physics 2020-12-02 Jan Perina , Vaclav Michalek , Ondrej Haderka

Current definitions of both squeezing operator and squeezed vacuum state are critically examined on the grounds of consistency with the underlying su(1,1) algebraic structure. Accordingly, the generalized coherent states for su(1,1) in its…

Quantum Physics · Physics 2019-11-01 Francesco Raffa , Mario Rasetti , Marco Genovese

We investigate non-classical effects such as fractional revivals, squeezing and higher-order squeezing of photon-added coherent states propagating through a Kerr-like medium.The Wigner functions corresponding to these states at the instants…

Quantum Physics · Physics 2007-05-23 C. Sudheesh , S. Lakshmibala , V. Balakrishnan

The study of nonclassical properties of two-mode quantum states is particularly useful in quantum information theory because of the possibilities of obtaining entanglement and other two-mode quantum correlations in these states. Here we…

Quantum Physics · Physics 2024-06-17 Kathakali Mandal , Anjali Jatwani , Amit Verma

An intriguing feature of type II$_1$ von Neumann algebra is that the entropy of the mixed states is negative. Although the type classification of von Neumann algebra and its consequence in holography have been extensively explored recently,…

High Energy Physics - Theory · Physics 2024-04-04 Haifeng Tang

Achieving synchronized quantum states within the quantum realm is a significant goal. This regime is characterized by restricted excitation occurrences and a highly nonclassical stable state of the self-oscillating system. However, many…

Quantum Physics · Physics 2025-04-15 M. Preethi , M. Senthilvelan

We evaluate the gravity-induced negativity volume of the generalized Wigner function in a hybrid system consisting of a particle in a two-localized superposition state and an oscillator. The generalized Wigner function can capture the…

Quantum Physics · Physics 2023-11-21 Daisuke Miki , Akira Matsumura , Kazuhiro Yamamoto

Nonclassicality filters provide a universal method to visualize the nonclassicality of arbitrary quantum states of light through negativities of a regularized Glauber-Sudarshan $P$ function, also denoted as nonclassicality quasiprobability.…

Quantum Physics · Physics 2014-10-06 B. Kühn , W. Vogel

A general analysis of squeezing transformations for two mode systems is given based on the four dimensional real symplectic group $Sp(4,\Re)\/$. Within the framework of the unitary metaplectic representation of this group, a distinction…

Quantum Physics · Physics 2009-10-28 Arvind , B. Dutta , N. Mukunda , R. Simon

This study investigates nonclassical effects of photons in the anisotropic quantum Rabi-Stark model by using a quantum dressed master equation. We analyze second- and higher-order correlation functions, and demonstrate that the nonlinear…

Quantum Physics · Physics 2026-03-31 Yong-Xin Zhang , Chen Wang , Qing-Hu Chen

Two-mode squeezing is central to entangled-photon generation and nonlinear interferometry, yet standard perturbative low-gain treatments and Gaussian formalisms can obscure the interference of photon-number amplitudes, especially in…

Quantum Physics · Physics 2026-02-11 Xuemei Gu , Carlos Ruiz-Gonzalez , Mario Krenn

The von Neumann entropy of various quantum dissipative models is calculated in order to discuss the entanglement properties of these systems. First, integrable quantum dissipative models are discussed, i.e., the quantum Brownian motion and…

Quantum Physics · Physics 2009-11-11 T. Stauber , F. Guinea

The reliable quantification of nonclassicality in quantum states under realistic decoherence remains a central challenge in advancing quantum technologies. Conventional quantifiers such as Wigner negativity, Mandel's $Q$-parameter,…

Quantum Physics · Physics 2026-05-15 K. M. Athira , M. J. Neethu , M. Rohith

We provide a classification of entangled states that uses new discrete entanglement invariants. The invariants are defined by algebraic properties of linear maps associated with the states. We prove a theorem on a correspondence between the…

Quantum Physics · Physics 2013-01-08 Roman V. Buniy , Thomas W. Kephart

There are quantum states of light that can be expressed as finite superpositions of Fock states (FSFS). We demonstrate the nonclassicality of an arbitrary FSFS by means of its phase space distributions such as the Wigner function and the…

Quantum Physics · Physics 2022-06-10 Anirban Pathak , J. Banerji

We have experimentally created a robust, ultrabright and phase-stable polarization-entangled state close to maximally entangled Bell-state with $ \% 98 $-fidelity using the type-II spontaneous parametric down-conversion (SPDC) process in…

Quantum Physics · Physics 2021-07-05 Ali Motazedifard , Seyed Ahmad Madani , J. Jafari Dashkasan , N. Sobhkhiz Vayaghan

Phase measurement using a lossless Mach-Zehnder interferometer with certain entangled $N$-photon states can lead to a phase sensitivity of the order of 1/N, the Heisenberg limit. However, previously considered output measurement schemes are…

Quantum Physics · Physics 2009-11-13 Yang Gao , Hwang Lee

Manipulating entanglement, which reflects non-local correlations in a quantum system and defines the complexity of describing its wave function, represents the extremely tough challenge in the fields of quantum computing, quantum…

Some non-classical properties such as squeezing, sub-Poissonian photon statistics or oscillations in photon-number distributions may survive longer in a phase-sensitive environment than in a phase-insensitive environment. We examine if…

Quantum Physics · Physics 2015-06-26 D. Wilson , J. Lee , M. S. Kim